Test 15-【沸腾英语】2024年高二英语(阅+完+七选五+语法+续写)五项全练

五项全练 高 二 92 阅读理解第 部分一 第一节 阅读下列短文，从每题所给的四个选项 (A、B、C 和 D) 中，选出最佳选项。 A Some trees can live for centuries or even millennia but the secrets behind their long life have puzzled scientists. However, new research has found that the ginkgo tree, which can live more than 1,000 years, doesn’t really show any expected effects of aging. Researchers examined growth rings taken from inside the trunks of 34 healthy ginkgo trees in two Chinese provinces, Jiangsu and Hubei. The trees ranged in age from 15 to 667 years old. They found that the ginkgoes didn’t stop growing as they aged, although the rings grew thinner. And increasing age wasn’t associated with changes in other indicators of tree health: leaf size, its ability to photosynthesize ( 光合作用 ) and seed quality. Researchers examined possible changes at the genetic level. The researchers compared cells from between the tree wood and bark and found that there was no change in the genes related to biological aging. They found that, no matter what their age, the trees produced chemicals that helped defend against outside stressors such as disease or drought. The study concluded that, in effect, old ginkgo trees stay healthy by preventing aging and maintaining their ability to resist outside dangers. “The trees showed no sign of aging as we would understand it,” said Howard Thomas, a professor at the University of Aberystwyth in Wales. “The researchers saw changes but nothing that could be related to what’s known to be age specifi c in other organisms. For anyone who looks to trees for the secret of life, this could be frustrating,” Thomas said. “To all intents and purposes, if it wasn’t for chance and other factors, they will never die. Probably that’s why plants are so successful.” “Some ginkgoes are thought to be as old as 3,000 years,” Thomas said, “but that doesn’t make them the world’s oldest tree. That honor goes to a pine found in the White Mountains of California, which is approximately 5,000 ye